Alexander in his free time had once read the biography of Hanns-Joachim Gottlob Scharff, who was a German interrogator during the Second World War.
He had been called the "Master Interrogator" of the Luftwaffe, and possibly of all Nazi Germany and he was also praised for his contribution in shaping U.S. interrogation techniques after the war.
And the primary way he made even tough captured GIs and commandos speak things beyond their name and serial number, was by portraying himself as their closest ally in this predicament, telling them that while he would like nothing more than to see them safely deposited in a POW camp; his hands were tied unless the prisoner gave him some more details that he requested to help him properly identify the prisoner as a true POW, or he would be forced to send them to a slave labor camps or worse, the gas chambers.